A DFT study for hydrogen storage application on pristine magnesium dicarbide (MgC) monolayer.

The hydrogen storage potential of pure MgC was systematically investigated using density functional theory (DFT) calculations. The phonon dispersion and molecular dynamics (AIMD) simulations confirmed the dynamic and structural stability of MgC, reinforcing its suitability as a promising hydrogen storage material. The electronic structure analysis revealed that pure MgC exhibits semiconducting behavior with a band gap of 0.25 eV, and transforms into a metallic state upon hydrogen adsorption. Hydrogen molecules were adsorbed onto the MgC surface physisorption, with an average adsorption energy of 0.286 eV, indicating moderate binding strength suitable for reversible hydrogen storage. Hirshfeld charge analysis demonstrated that MgC transfers 0.041 e, 0.139 e, and 0.259 e to 1, 4, and 8 hydrogen molecules, respectively, highlighting charge redistribution upon adsorption. The calculated hydrogen storage capacity of 2.05% suggests a feasible adsorption mechanism. Additionally, AIMD simulations at 400 K confirmed that hydrogen adsorption does not induce significant distortions in the MgC framework, further validating its thermal and mechanical stability. These findings underscore the potential of MgC as an efficient hydrogen storage material for sustainable energy applications, offering a promising pathway for the development of next-generation clean energy technologies.